Re: [PATCH] mm/hugetlb: Fix build with !ARCH_WANT_HUGE_PMD_SHARE

[Peter Xu]

On Wed, Mar 10, 2021 at 11:21:50AM -0800, Mike Kravetz wrote:
> On 3/10/21 10:53 AM, Peter Xu wrote:
> > want_pmd_share() is undefined with !ARCH_WANT_HUGE_PMD_SHARE since it's put
> > by accident into a "#ifdef ARCH_WANT_HUGE_PMD_SHARE" block.  Moving it out
> > won't work either since vma_shareable() is only defined within the block.
> > Define it for !ARCH_WANT_HUGE_PMD_SHARE instead.
> > 
> > Fixes: 5b109cc1cdcc ("hugetlb/userfaultfd: forbid huge pmd sharing when uffd enabled")
> 
> That commit id is from Andrew's tree and I don't think it is stable.
> There is a different id in the next tree.  Not exactly sure how this is
> supposed to be handled.

I see - it'll be even better if this patch can be squashed into it.

> 
> > Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> > Cc: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
> > Cc: Axel Rasmussen <axelrasmussen@xxxxxxxxxx>
> > Reported-by: Naresh Kamboju <naresh.kamboju@xxxxxxxxxx>
> > Tested-by: Naresh Kamboju <naresh.kamboju@xxxxxxxxxx>
> > Signed-off-by: Peter Xu <peterx@xxxxxxxxxx>
> > ---
> >  mm/hugetlb.c | 8 +++++---
> >  1 file changed, 5 insertions(+), 3 deletions(-)
> 
> Thanks Peter,
> Not your fault, but that header file is a bit of a mess.
> 
> Reviewed-by: Mike Kravetz <mike.kravetz@xxxxxxxxxx>

I'm still guilty on not noticing this before since I still could..  I think it
gives me some more clue to make less such mistake in the future.

Thanks for taking a quick look, Mike!

-- 
Peter Xu